U.S. patent number 3,880,757 [Application Number 05/351,588] was granted by the patent office on 1975-04-29 for filtering system.
Invention is credited to Gary Thomason.
United States Patent |
3,880,757 |
Thomason |
April 29, 1975 |
Filtering system
Abstract
A filtering system for cooking vessels includes first and second
stage filters and a pump therebetween. Hot cooking oil is
continuously passed through a first stage filter wherein larger
particles are removed, after which the oil is passed through a
second stage filter wherein small particles are removed. The media
in the second stage filter comprises thin, fibrous paper material
presenting interlocking fibers between layers in a multilayer roll,
with the hot cooking oil being pumped axially through such roll.
Both the first and second stage filter media are contained within
disposable cans easily exchanged but to which an oiltight
connection is made.
Inventors: |
Thomason; Gary (Beaverton,
OR) |
Family
ID: |
26874600 |
Appl.
No.: |
05/351,588 |
Filed: |
April 16, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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178736 |
Sep 8, 1971 |
3759388 |
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Current U.S.
Class: |
210/167.28;
210/236; 210/443; 210/445 |
Current CPC
Class: |
B01D
29/073 (20130101); B01D 29/072 (20130101); B01D
35/18 (20130101); B01D 29/902 (20130101); B01D
29/072 (20130101); B01D 29/073 (20130101); B01D
29/902 (20130101); B01D 2201/287 (20130101) |
Current International
Class: |
B01D
29/07 (20060101); B01D 29/01 (20060101); B01D
35/18 (20060101); B01D 35/00 (20060101); B01d
027/08 () |
Field of
Search: |
;210/167,443,439,453,440,454,445,438,437,444.3,450,DIG.17,497.1,236-238 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Granger; Theodore A.
Attorney, Agent or Firm: Klarquist, Sparkman, Campbell,
Leigh, Hall & Whinston
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of my copending
application Ser. No. 178,736, filed Sept. 8, 1971, entitled
"Filtering System for Deep Fat Cooking Vessel" now U.S. Pat. No.
3,759,388.
Claims
I claim:
1. In a filtering system for cooking oil, means for providing a
disposable and replaceable filter unit readily engageable in
sealing connection with said filtering system, said means
comprising:
a manifold base adapted to receive said filtering unit in
supporting relation and provided with separate connection means for
supplying the entrance and exit of oil,
said filtering unit comprising a cylindrical can having filtering
media therein for filtering said oil by passage of said oil
therethrough, said cylindrical can having a top and bottom joined
to the cylindrical wall of said can, said top and said bottom are
provided with substantially aligned apertures, said filtering media
having a hollow core therethrough in alignment with said apertures,
said core being a tube extending from the bottom to the top of said
can, said tube having a plurality of openings therein constructed
and arranged at the end of said tube adjacent the top of said can,
the top of said filtering media being spaced from the underside of
the top of the can to thereby define a space therebetween,
an upstanding spindle joined to said manifold base and having a
central passage communicating with one of said connection means in
said manifold base, said spindle also having radial passage means
communicating between said central passage and cooperating with
said openings in said tube peripherally arranged around said
spindle, said spindle being adapted to be received through said
aligned apertures in said can, said radial passage means
communicating radially outwardly through said openings in said tube
into the said space defined by the underside of the top and the top
of the filtering media,
said can having one or more openings in the bottom outside said
first of said aligned apertures for communicating with the other of
said connection means in said manifold base,
a substantially flat cover plate having an aperture therethrough,
said spindle adapted and constructed to project upwardly through
the aligned aperture in said top and through the aperture of said
flat cover plate, knob means adapted and constructed to engage a
portion of the spindle projecting through said flat cover plate,
said knob means including means to draw said cover plate toward
said spindle and said can whereby said cover plate forces
downwardly said can to provide a sealing relation between the
bottom of said can and the manifold base around said spindle and
openings.
2. The apparatus according to claim 1 including sealing means for
preventing escape of oil from said aligned apertures outside the
area immediately surrounding said spindle, and for preventing
escape of oil from said openings outside of the area of said can
bottom as said can is forced downwardly.
3. The apparatus according to claim 1 including sealing means
comprising O-ring seals surrounding said spindle on the top of said
manifold base for engaging said bottom of said can, said other of
said connection means communicating with said can between said
O-ring seals.
4. The apparatus according to claim 3 wherein said manifold base is
provided with a depression well between said O-ring seals
communicating with said other of said connection means, said
depression well extending around the top of said manifold base.
5. The apparatus according to claim 1 wherein the upper portion of
said spindle is provided with a threaded extension positioned
through the said aperture of said flat cover plate and wherein said
knob means for drawing said cover plate toward said top of said can
includes means for threadably engaging said extension and bearing
against said cover plate.
6. The apparatus according to claim 1 wherein said cover plate is
provided with a circular groove on the underside thereof for
receiving the rim of said can, for centering said can and forcing
said can downwardly along the cylindrical wall thereof.
7. The apparatus according to claim 6 wherein said manifold base is
provided with a beveled wall for engaging the inside rim of the
bottom of said can and cooperating in providing the centering of
said can as said can is forced downwardly.
8. The apparatus according to claim 1 wherein said filtering media
comprises a multilayer roll of thin, fibrous paper material
presenting interlocking fibers between layers.
9. The apparatus according to claim 1 including further sealing
means comprising an O-ring seal between an upper shoulder of said
spindle and the top inside of said can.
10. The apparatus according to claim 1 including further sealing
means comprising a first O-ring seal between the bottom of said
cover plate and the top of said can, and a second O-ring seal
between said means for drawing said cover plate toward said spindle
and said cover plate.
11. The apparatus according to claim 1 wherein a portion of said
can top is located between said spindle and said cover plate, with
sealing means bearing against the top of said can proximate the top
of said spindle.
12. In a filtering system for cooking oil, means for providing a
disposable and replaceable filter unit readily engageable in
sealing connection with said filtering system, said means
comprising:
a manifold base adapted to receive said filtering unit in
supporting relation and provided with separate connection means for
supplying the entrance and exit of oil,
said filtering unit comprising a cylindrical can having filtering
media therein for filtering said oil by passage of said oil
therethrough, said cylindrical can having a top and bottom joined
to the cylindrical wall of said can, wherein said top and said
bottom are provided with substantially aligned apertures,
an upstanding spindle joined to said manifold base and having a
central passage communicating with one of said connection means in
said manifold base, said spindle also having radial passage means
communicating between said central passage and the surface of said
spindle at one or more locations upwardly from said manifold base,
said spindle being adapted to be received through said aligned
apertures in said can, said radial passage means communicating
radially outwardly into the filtering media in said can within the
axial dimension of said can between said apertures in the top and
bottom of said can with said can in position upon said manifold
base,
said can having another opening in the bottom of said can outside
said first of said aligned apertures, said other of said connection
means being provided with an upstanding tube extending through said
other opening between said media and the side of said can, said
media and said spindle being off-center with respect to the axis of
said can,
a substantially flat cover plate having an aperture therethrough,
said spindle adapted and constructed to project upwardly through
the aligned aperture in said top and through the aperture of said
flat cover plate, knob means adapted and constructed to engage a
portion of the spindle projecting through said flat cover plate,
said knob means including means to draw said cover plate toward
said spindle and said can whereby said cover plate forces
downwardly said can to provide a sealing relation between the
bottom of said can and the manifold base around said spindle and
openings.
13. The apparatus according to claim 12 wherein said media
comprises cord characterized by a fibrous exterior, said cord being
wound in an overlapping weave which becomes a tighter weave in a
direction taken by said cooking oil in passing through said filter
media, to provide a plurality of pocket-like semi-enclosures for
trapping particles from said cooking oil,
said last mentioned media being wound on a perforate tube within
said can and enclosing said spindle, said radial passage means in
said spindle extending outwardly from said central passage for
receiving oil from the last mentioned media through said
perforations.
14. The apparatus according to claim 12, including a first O-ring
seal on the top of said manifold base and around said spindle for
bearing against the bottom of said can, and a second O-ring seal on
the top of said manifold base around the first O-ring seal and
around said upstanding tube for also bearing against the bottom of
said can.
Description
BACKGROUND OF THE INVENTION
This invention relates to a filtering system for cooking vessels,
and particularly to a filtering system for removing small particles
and employing exchangeable filtering elements.
Many restaurants employ deep fat fryers wherein the heated cooking
oil is maintained at a high temperature for an extended period of
time in which food articles, usually having some kind of batter or
coating applied thereto, are cooked in fairly large quantities in
the same heated oil. When oil of this type is continuously used,
foreign matter retained in the oil, e.g., some of the batter or
coating applied to the food articles, will rapidly carbonize or
char. These overheated materials accelerate rapid breakdown and
cause hydrolysis oxidation and polymerization of the fat. Visible
signs of excessive foreign matter will soon appear as, for
instance, the absorbed food particles smoke or carbonize at a
temperature lower than a smoke or flash point expected of the
cooking oil or fat. Uneven browning of food and flavor and odor
transfer occur, and the final result is the carbonizing, foaming
and rancidness of the fat.
If the cooking oil in a particular vessel has been used for an
entire day, it is usually necessary that the oil be filtered or
replaced. This is, of course, a time consuming and also somewhat
dangerous operation considering the high temperature to which the
oil is usually heated. Customarily, the oil is removed from the
deep fat cooking vessel and slowly passed through a filtering media
such as diatomaceous earth to remove undesired particles.
Unfortunately, the use of diatomaceous earth, while removing some
particles, increases the content of the diatomaceous earth itself
in the cooking oil. Various other straining means have been used
for filtering oil removed from a cooking vessel such as
conventional pleated paper cartridges, cloth bags, and the like.
However, these methods do not really result in removing particles
from the food as bring about the undesirable flavor qualities and
rancidness of the fat, after a few days' use, because smaller
particles are not removed. In general, about three days' use can be
expected of a given quantity of cooking oil operated substantially
continuously at high temperatures, and after such time the oil is
ordinarily discarded which, of course, represents a major expense
in the case of many restaurant operations.
Many attempts have been made heretofore at continuous filtering of
cooking oil by continuously withdrawing cooking oil from the vat or
vessel, filtering the same, and returning the same to the cooking
vessel. Unfortunately, such methods have not been practical because
of limited filtering accomplished. In general, pleated cartridges
or the like have been employed where the cooking oil essentially
passes perpendicularly through a sheet of filter material. Various
strainers or similar devices have been utilized on a continuous
basis in an effort to remove some foreign material from the oil.
Unfortunately, none of these expedients have resulted in the
removal of sufficiently fine particles from the oil to extend the
life of the oil materially beyond the limits mentioned above.
In accordance with my previous application, high temperature
cooking oil from the deep fat cooking vessel is passed through
first and second filter stages by pumping means adapted to operate
at low pressures, while continuously circulating the cooking oil
from the cooking vessel through the first and second filter stages
and back to the cooking vessel. The first filter stage is adapted
for removing food particles down to a given size, e.g., particles
of 100 microns or greater in size. The second filter stage
comprises a filtering media in the form of a thin, fibrous paper
material presenting interlocking fibers between layers in a
multilayer roll. The hot cooking oil is passed longitudinally
through the roll, i.e., substantially along the layers, through the
fibers extending between layers, by means of which particles of an
extremely small size are removed. According to tests, the second
stage of filtering, following the first stage, removes particles of
greater size than 7/100 of a micron. Removal of particles of this
size acts substantially to clarify the cooking oils, and materially
extends the life thereof beyond that heretofore thought
possible.
In carrying out of filtering for extended periods of time, the
filtering media or elements eventually become clogged, having
filtered and removed a great quantity of foreign matter from the
cooking oils passing therethrough. A pump bypass prevents undue
pressure from building up in the system, but nevertheless it is
desired that the filtering elements be replaced from time to time.
For this purpose, the filtering elements are contained within
cylindrical cans which are disposable and replaceable. It has been
found desirable to render the replacement of these filtering
elements more easily accomplished in a shorter period of time by
inexperienced personnel without requiring the undue soiling of the
hands or contamination of surroundings. It is also desired that a
certain seal be accomplished for the flow of heated cooking oil
under pressure into and out of the replaceable filtering elements
and the connections attaching thereto.
SUMMARY OF THE INVENTION
According to the present invention, a filtering media is provided
in a cylindrical can having upper and lower apertures therein
through which a base manifold-mounted spindle may extend. The
manifold, as well as the spindle, include passages for the
conduction of oil to and from the media in the filter. The spindle
is employed as a means engageable for not only positioning the can
and coupling oil thereto, but also as means for exerting axial
pressure against the can and forcing upper and lower can surfaces
in secure contact with sealing members, whereby escape of oil is
prevented.
In a particular embodiment, a hand-operated knob is threadably
engaged to the upper portion of the spindle, and is easily operated
by inexperienced personnel for presenting appreciable pressure as
required by the sealing means. At the same time, the filtering
elements are readily removed and replaced, and the exterior of the
can does not become contaminated with oil, but is readily grasped
by the individual for replacement and the installation of a new
can.
Accordingly it is an object of the present invention to provide an
improved filtering system for cooking oil and the like.
It is a further object of the present invention to provide an
improved filtering system for cooking oil and the like wherein
replaceable filter elements are employed.
It is a further object of the present invention to provide an
improved filtering system employing replaceable filter elements
wherein such replacement is easily accomplished by hand for making
secure connection with a filtering element and without
contaminating the exterior of the filtering elements whereby the
same may be grasped by hand for replacement.
It is another object of the present invention to provide an
improved filtering system employing replaceable filtering elements
in the form of can-enclosed filter media, where the can is readily
sealed and positioned by hand-operation, but may be readily removed
by hand, and where the exterior of the can is essentially grease
free.
The subject matter which I regard as my invention is particularly
pointed out and distinctly claimed in the concluding portion of
this specification. The invention, however, both as to organization
and method of operation, together with further advantages and
objects thereof, may best be understood by reference to the
following description taken in connection with the accompanying
drawings wherein like reference characters refer to like
elements.
DRAWINGS
FIG. 1 is a perspective view of a filtering system according to the
present invention including a cabinet therefor;
FIG. 2 is a vertical cross section of a second stage filter
according to the present invention;
FIG. 3 is a horizontal cross section of the FIG. 2 filter taken at
3--3 in FIG. 2;
FIG. 4 is an enlarged, partially broken away, vertical cross
section of the FIG. 2 filter;
FIG. 5 is a vertical cross section of a first stage filter
according to the present invention;
FIG. 6 is a horizontal cross section of the FIG. 5 filter taken at
6--6 in FIG. 5; and
FIG. 7 is a partial vertical cross section of the filter of the
present invention illustrating alternative sealing means.
DETAILED DESCRIPTION
Referring to the drawings and particularly to FIG. 1, a filtering
system according to the present invention is suitably housed in a
cabinet 10 provided with a hinged lid 11 and pipe connections 12
and 14, the latter leading respectively to and from a heated
cooking vessel or the like as employed for frying foods. The
cooking oil is drawn into a first filter stage or prefilter sump 16
and from there passes via line 18 to a high temperature mechanical
seal pump 20, typically operating at the speed of 1725 r.p.m. as
driven by a motor 23. A suitable pump is a Model FH32 pump
manufactured by Viking Pump, Cedar Falls, Iowa. This type of pump
includes a bypass or pressure relief valve which suitably operates
at a pressure of 25 p.s.i. whereby the pump will not provide a
higher pressure. The relief valve bypasses liquid from the
discharge back to the suction side of the pump for preventing the
buildup of more than the desired pressure in the discharge
line.
From pump 20, the oil passes through line 22 to second stage filter
24. As hereinafter more fully described, the second stage filter 24
employs a media or element for removing very fine particles and
contaminants from the oil, e.g., down to 7/100 of a micron, leaving
a substantially pure and renovated oil for return to the cooking
vessel.
The second stage filter, generally indicated at 24, is more fully
illustrated in vertical cross section in FIG. 2, as well as in
horizontal cross section as taken at 3--3 in FIG. 2, and in more
detailed vertical cross section in FIG. 4. The filter media or
element 26 is contained within cylindrical can 28 suitably formed
of aluminum or tin-coated steel. The filter media or element 26
comprises a multilayer roll of thin fibrous paper material, fairly
tightly wound, presenting interlocking fibers between layers in the
multilayer roll. For instance, such paper may comprise soft, thin,
slack-sized paper generally made from pulp having short fibers,
e.g., the material may be treated in a manner for cutting fibers
and/or made from hard wood. Sulphite pulp may be used. A strong
caustic extraction may be employed for softening. In any case, the
finished paper is preferably loose and thin having a surface with
many upstanding fibers. A cardboard center tube 30 is closely
received upon a cardboard core 32, the latter being fairly heavy
and of substantially impervious construction and closely received
within tube 30. The filter media 26 substantially completely fills
the can 28 from tubes 30 and 32 to the outside cylindrical wall of
the can.
The bottom 33 of can 28 is provided with a central aperture defined
by an in-rolled wall 34 about which tube 32 is closely received.
The aperture at 34 has an inside diameter only slightly greater
than the outside diameter of a cylindrical, metal, central spindle
36 extending upwardly from manifold base 38, the latter being
secured to the bottom of the cabinet. Spindle 36 extends upwardly
within tube 32 for approximately the height of can 28, and at the
top thereof is provided with a longitudinal, threaded portion 40 of
smaller diameter than the central part of the spindle and received
through aperture 42 in top 44 of can 28. The upper shoulder 46 of
spindle 36 has a circular seat for receiving O-ring seal 48 which
becomes depressed against the underside of top 44 as hereinafter
more fully described.
Spindle 36 is provided with a second threaded portion 50 at the
bottom thereof received within threaded socket 52 in manifold base
38, socket 52 communicating with radial passage 54 to which line 22
connects at the outer circumference of manifold base 38. Threaded
portion 50 is threadably engaged in socket 52 for drawing spindle
36 up tight against the top surface 56 of the manifold base. The
spindle 36 is further supplied with an axial passage 58
communicating with socket 52, and also communicating with radial
passages 60 extending from passage 58 outwardly to the region
immediately around spindle 36, between spindle 36 and core 32. Core
32 is V-notched at the top, suitably down to the location of
passages 60, for enabling the flow of oil from passages 60 to
region 64 under top lid 44 and immediately above media 26. The
media 26 is spaced from the can top 44, as is tube 30, so oil
delivered under pressure in line 22 from pump 20 will be forced
into region 64, and from thence vertically downward to media 26. In
order to accomplish the proper spacing to provide the aforesaid
region 64, the can top 44 is beveled upwardly at 66 defining an
upraised central flat region in spaced relation from media 26.
To prevent leakage of oil downwardly through the aperture at 34,
the base manifold is provided with an O-ring seal 68 bearing
upwardly against can bottom 33.
The oil within media 26 has a tendency to move or compact the
filter media downwardly. For this reason, as well as for preventing
paper migration in the oil, filter screens 72 and 74 are located at
the bottom of the can just above can bottom 33. It will also be
observed that the can bottom is similar in shape to the can top,
having a bevel at 76, whreby the can is provided with an oil outlet
region in and around screens 72 and 74. The oil then leaves can 28
through one of a plurality of apertures 78 spaced about the can
bottom. The bevel 76 is also compressed against large O-ring seal
80 disposed in concentric fashion around spindle 36, and concentric
with O-ring seal 68. Between these O-ring seals is located a
circumferential channel well or depression 82, also concentric with
the O-rings and spindle 36. Thus, the oil leaving the can through
openings 78 is received within depression 82, leaving such
depression via passage 84 communicating with tubular connection 12
for returning the oil to the cooking vessel.
The can 28 is compressed axially against O-ring seals 68 and 80 by
means of a circular, disc-shaped cover plate 86 having a groove 88
for receiving upper can edge or rim 90 where the can top is crimped
or secured to the cylindrical wall of the can. Plate 86 is
centrally apertured at 92 for receiving threaded portion 40
extending upwardly from spindle 36, the threaded portion 40 being
threadably engaged by knurled or indented knob 94 which may be
turned by hand for exerting pressure against the top of plate 86.
If so desired, knob 94 may be integral with plate 86, but in any
case the knob 94 is easily turned by hand for compressing can 28
downwardly whereby the top 44 of the can makes thorough sealing
connection with O-ring seal 48, and whereby the bottom 33 of the
can makes thorough sealing connection with O-ring seals 80 and 68.
The lower rim 98 of the can is received against beveled wall 100 of
the manifold base, such beveled wall being circumferential with
spindle 36 and adapted for centering the can and allowing the
sealing pressue to be applied as described without distorting the
can to an undesired extent. The bevel forces the lower rim slightly
outwardly. Sufficient sealing pressure will generally be secured
through hand turning the knob 94 before rim 98 reaches the bottom
of beveled wall 100.
About the outer perimeter of manifold base 38, which is suitably
circular in outline, is disposed a well 102 for catching any excess
oil which may be inadvertently spilled when the filter is
exchanged. When the filter is operating properly, substantially no
leakage will occur into well 102, but when the filter is withdrawn
upwardly, the additional peripheral catch basin is desired as a
precaution, and may be easily wiped clean.
It will be readily seen that the installation and exchange of
canned filters is enhanced by the construction described. The
second stage filter media is substantially self-contained within a
can 28 which is readily installed by inserting the same upon
spindle 36, applying plate 86, and turning knob 94 with a moderate
amount of torque until reasonably tight. The seals 48, 68 and 80
are engaged so that oil flowing into the filter is kept within the
central region of spindle 36 by O-ring seal 68 at the lower end of
the spindle, while the oil is prevented from leaking through
apertures 92 by means of O-ring seal 48 at the top of the spindle.
The oil is thereby directed to region 86 within the otherwise
closed top 44 of the can, the oil then flowing downwardly through
the filter media and exiting through apertures 78 into depression
82. The oil exiting from the filter is confined within the region
of depression 82, between O-ring seals 68 and 80, whereby there is
substantially no mixing of inlet oil and outlet oil, nor is leakage
permitted during pressurized operation past seal 80 to the
surrounding well 102. After the filtering lifetime of the second
stage filter 24 is reached, the same is readily removed by first
loosening and removing knob 94 and plate 86, and then by removing
the can 28 from spindle 36. The can is discarded and a replacement
is placed upon spindle 36 in the manner described above. Not only
is changing of filters achieved in a rapid manner, but also the oil
passage is well confined within can 28 without requirement of
excessive or complex cartridge-engaging mechanism. Moreover, the
exterior of can 28 is kept clean, whereby the same may be readily
handled by cooking personnel, and whereby no objectionable layer of
grease or oil is accumulated on the exterior of the equipment.
Referring now to FIGS. 5 and 6, illustrating an improved prefilter
sump or first stage filter, generally indicated at 16, the
construction is similar in many respects to the mating second stage
filter 24. Can 28' encloses a filter media 104 wound on a tube 110
located around a vertical spindle 106, spindle 106 extending
upwardly from manifold base 38' which is in turn secured to the
bottom of the cabinet. However, the spindle 106 is off-center in
the can whereby the media 104 clears a vertically upstanding inlet
tube 108 press-fitted into manifold base 38' for communicating with
passage 110 to which inlet line 14 may connect. The tube 108
extends through a substantially matching aperture in the underside
of the can. It will be observed that the upward extension of pipe
108 places the inlet above the level of material which may collect
in can 28', and also prevents undue backflow when the can is
removed and replaced. The media 104 suitably comprises a nylon
filament or cord of about 1/64 of an inch in diameter which is
loosely spun to present a very fibrous or fuzzy surface, i.e., with
a multiplicity of filaments extending radially outward therefrom. A
filter of this general type is known as a Ful-flo filter of the
honeycomb filter type manufactured by Commercial Filters
Corporation, Lebanon, Ind. The particular filter herein described
is more tightly wound at the interior, i.e., upon perforated center
tube 110, to present orifices on the order of 100 microns in
diameter. The cord is bobbin-wound, producing an overlapping weave
having a diamond appearance, and which is looser or more open
toward the outer periphery of media 104. The outside orifices are
on the order of 3/16 square inch. A multiplicity of honeycomb
pockets are provided which funnel to the tighter weave toward the
center tube 110. Approximately 30 layers of cord are wound upon
tube 110 between the inner and outer peripheries of the filter
media.
As oil enters the prefilter sump 16 via tube 14, larger particles
become entrained near the exterior of media 104 and splash or fall
toward the bottom of the media and around tube 108 toward the
bottom of can 28'. Smaller particles pass into the honeycomb
pockets in the media and become lodged in the pockets with the
media removing particles larger than approximately 100 microns. The
filtered oil with particles smaller than 100 microns passes through
perforations 112 in tube 110 and into the region 114 between tube
110 and spindle 106. From there the oil with small particles passes
through passages 60' into central passage 58' of spindle 106,
communicating with threaded socket 52' and passage 116 for
connection to line 18 leading to the pump. It will be observed that
the pump thus draws the oil through the prefilter sump and toward
the second stage filter 24 hereinbefore described. As in the case
of the previously described filter, the spindle 106 has a lower
threaded portion 50' threadably secured within threaded socket 52',
and over which indented aperture 34' in the can bottom 33' is
closely received. O-ring seal 68' seals the outlet connection so
any oil escaping through aperture 34' will not leak therearound
into the region where inlet oil may be present, nor can the inlet
oil leak into the outlet oil passages. An O-ring seal 80', bearing
against the downwardly beveled portion of the can bottom, prevents
leakage of inlet oil to the outside environment. A well 102' is
present for such slight leakage as may inadvertently occur when
filter cans are exchanged.
The can top 44' is provided with an opening 42' through which
threaded portion 40' of the spindle 106 extends. Also, a plate 86'
having an aperture 92' is received upon threaded portion 40', with
a knurled or irregular knob 94' threadably engaging threaded
portion 40' for exerting downward pressure on plate 86'. Plate 86'
has a lower groove 88' into which the upper can rim 90' is
received, whereby hand torque applied to knob 94' is effective for
urging the can downwardly and making an even, sealing connection
between the can bottom and O-ring seals 68' and 80' on the manifold
base, as well as making a sealing connection between O-ring seal
48' disposed upon upper shoulder 46' of spindle 106 and the
underside of can top 44'.
As appears, this first stage filter or prefilter sump is also
readily installed and exchanged in a simple manner without the
requirement of tools and without requiring the undue soiling of
hands by cooking personnel when the filter becomes clogged and
apparent circulation becomes slowed with the pump bypass operating
as described above. The filter media contained cans are simply
exchanged.
While the foregoing sealing construction involving seals 48 and 48'
respectively for bearing against the underside of can tops 44 and
44' is preferable from the standpoint of efficiency and economy, a
second sealing construction has also been found efficacious as an
alternative. This alternative is depicted in FIG. 7 and is
particularly illustrated with respect to the second stage filter
generally hereinbefore referred to employing reference numeral 24.
Thus, a central spindle 36" is provided with an upper threaded
portion 40" extending through opening 42" in can top 44" as well as
through an opening 92" in plate 86". A hand-operated knob 94"
threadably engages portion 40". However, instead of the O-ring seal
being provided on the upper shoulder of spindle 36", an O-ring 118
is disposed on a grooved recess on the lower side of plate 86" for
bearing against the can top 44". Moreover, another O-ring seal 120
is received in a lower groove in knob 94" and bears against the top
of plate 86". Thus, when the knob 94" is drawn up by hand, any oil
which may escape through opening 42" will be prevented from exiting
in a radial direction by the O-ring seals 118 and 120.
Considering the general operation of the filtering system according
to the present invention, heated cooking oil from a cooking vessel
or the like is continuously circulated through prefilter sump 16,
pump 20, and second stage filter 24 and returned to the cooking
vessel, with the prefilter sump 16 removing food particles and the
like down to about 100 microns before the hot cooking oil is drawn
into pump 20. Pump 20 forces the oil up through spindle 36 and
lengthwise, i.e., axially, from top to bottom through the filter
media 26 of the second stage filter. In both the prefilter sump and
in the second stage filter, the oil is passed through a
configuration of interlocking fibers for removing undesired
particles. The nylon thread of pre-filter sump 16 removes the
undesired particles down to a predetermined size, while the
interlocking fibers between sheets of the multilayer roll in the
second stage filter 24 remove particles down to an extremely small
size, the hot cooking oil as it passes downwardly in the second
stage filter encountering an enormous number of such fibers. It has
been found that filtering is sufficiently effective so that in some
cases the cooking oil can be utilized for an extended period of
time, far greater than heretofore thought possible.
It will be seen that the filtering system according to the present
invention not only enhances the quality of filtering but also
renders the changing of filter elements easily accomplished by
hand. No tools are necessary, and cooking personnel can easily
change filter elements by conveniently changing cylindrical cans
without soiling hands or cooking surroundings. The cover 11 of
cabinet 10 is raised, and the filtering apparatus is switched off
electrically by means not shown. The hand-operated knobs are
disengaged, and the cans are conveniently removed by hand and
discarded after which replacement cans are installed within a
relatively short time. The required pressure to prevent leaking is
easily provided by hand without a complex or expensive mechanical
structure. The sealing pressure is symmetrically applied with one
hand adjustment.
While I have shown and described several embodiments of my
invention, it will be apparent to those skilled in the art that
many changes and modifications may be made without departing from
my invention in its broader aspects. I therefore intend the
appended claims to cover all such changes and modifications as fall
within the true spirit and scope of my invention.
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